In apparatuses for examination (visualization) for use in inspection of industrial products and/or medical examination, optical fiber-based image fibers are employed. The apparatuses of this type are mainly used in visualization (diagnosis) of internal defects inside products or diseased parts inside the body.
When making repairs on a welded portion within a pipe in an industrial product or giving therapy on the inside of a human body, laser light is employed. In guiding laser light to a target portion (for example, a welded portion in a pipe or a portion to be treated inside a human body), optical fibers are employed.
The internal visualization techniques using image fibers, and on the other hand, the repair/therapy techniques involving guiding laser light to the inside as described above, have developed independently of one another. In other words, these techniques are in totally different fields thus far.
Recently, for repair of a defect in piping or therapy of a diseased portion in a human body, a composite optical fiber has been proposed. The composite optical fiber is formed by combining, for example, an energy transmission fiber (energy transmission fiber for laser light) with image fibers (image fibers for visualization/examination). The energy transmission fiber is, for example, a large-diameter optical fiber. The image fiber is, for example, a small-diameter optical fiber having a diameter smaller than that of the large-diameter optical fiber. A large number of the small-diameter optical fibers (image fibers) are placed around a large-diameter optical fiber (an energy transmission fiber).